1. Field of the Invention
The present invention relates to a system and mechanism for directing the leading edge of a continuous form onto a stack, and more particularly, to a device for appropriately directing the leading sheet(s) of a continuous form to begin a stack of forms.
2. Description of Background Information
Refolding and stacking of pre-folded continuous form paper is accomplished either by passive (gravity fed) stackers or by active stacking systems. Passive stackers may use a wire basket (or other box-shaped configuration) in combination with fixed guides. Active stackers use various devices positioned alongside the stacking platform, such as rotating paddles or air jets, to ensure that a stack of continuous form paper stacks correctly. However, laying the first few sheets of a stack is problematic with both passive and active stackers, since both kinds of stackers have no facility for appropriately placing the leading edge depending on the fold orientations encountered such that subsequent folds will develop correctly.
For example, with fan-fold continuous forms of paper or label stock, even after unfolding for printing, folds tend to remain in the continuous form in their original direction or orientation ("fold memory"), alternating between outside folds and inside folds between sheets. In this context, an "outside" fold is one that enters the printer with the fold cusp pointing upward, and an "inside" fold is one that enters the printer with the fold cusp pointing downward. Depending where the last discrete sheet of the form is separated, a leading fold following the leading edge of the form (usually formed at a perforation between sheets) may have either of an outside or inside orientation. Accordingly, a leading fold following the leading edge has a fold cusp pointing up ("outside") or down ("inside").
If the first sheet arriving at the stacking platform arrives such that second sheet folds over in the same direction of the fold memory of the leading fold, subsequent folding of the continuous form will encounter only a small chance of misfolding. However, if the first sheet arriving at the stacking platform arrives such that second sheet folds over against the direction of the fold memory of the leading fold, then all subsequent folds will be folded against the original fold orientation or "fold memory," and misfolding and mis-stacking of the continuous form media will likely occur.
Further, in a laser printer using pre-folded continuous forms, mis-stacking and misfolding often occurs when the toner-fusing or fixing rollers "iron" out the existing folds at the perforations between sheets of the continuous form. As a result, the form folds lose a portion of "fold memory," and tend not to refold easily into a stack. With high speed printers, misfolding and mis-stacking is further exacerbated.
Even when a passive or active stacker may reliably stack a continuous form when a group of initial sheets is properly laid down and folded, an operator must manually lay the first sheet. If sheet feeding is automatic, the operator must still ensure that the leading sheet is in the proper orientation for which the stacker is designed, and may be forced to remove the continuous form media, rotate the media input stack, and replace the media in the printer to orient the leading sheet properly.